Bitcoin-Qt: massive header and cpp cleanup

- try to enforce the same style to all Qt related files
- remove unneeded includes from the files
- add missing Q_OBJECT, QT_BEGIN_NAMESPACE / QT_END_NAMESPACE
- prepares for a pull-req to include Qt5 compatibility

src/qt/bitcoinunits.h

@@ -9,6 +9,8 @@
 */
 class BitcoinUnits: public QAbstractListModel
 {
+    Q_OBJECT
+
 public:
     explicit BitcoinUnits(QObject *parent);
 
@@ -58,6 +60,7 @@ public:
     int rowCount(const QModelIndex &parent) const;
     QVariant data(const QModelIndex &index, int role) const;
     ///@}
+
 private:
     QList<BitcoinUnits::Unit> unitlist;
 };